Synthesis of fluorinated molecules possesing high optical non-linearity

ABSTRACT

A compound of formula (I) wherein R′, R″, R′″, R″″, R′″″ can be selected from the group consisting of alkyl, aryl, a heteroatom, substituted alkyl and substituted aryl groups for use as a chromophore in electro-optic devices.

This application is based on Provisional Application 60/278,762 filedMar. 27, 2001.

FIELD OF THE INVENTION

The present invention relates to novel organic chromophores and methodsof making and using the same.

BACKGROUND OF THE INVENTION

Known materials for use in electro-optic devices include both organicand inorganic materials. Semiconductor materials such as galliumarsenide, organic crystalline materials and organic materials preparedby sequential synthesis methods are used as well as electrically poledpolymer films containing organic chromophores incorporated eitherphysically to form composites or chemically to form homopolymermaterials. See Kirk-Othmer Encyclopedia of Chemical Technology, 4^(th)Edition, Volume 17 (John Wiley & Sons, New York, 1995) pp. 288–302.

When an electric field is applied to electro-optic materials, the highlypolarizable electrons in those materials change significantly resultingin an increase in the index of refraction of the materials and adecrease in the speed of light passing through the materials. The changein the index of refraction can be used to impose electric signals ontooptical signals to switch optical signals in a network or to control abeam of light.

The most commonly used inorganic material is lithium niobate whichpossesses an electro-optic coefficient on the of 35 pm/V which resultsin a typical drive voltage of about 5 volts. Because lithium niobate hasa high dielectric constant which results in velocity mismatch ofelectric and optical waves propagating in the material, a shortinteraction length and limiting bandwidth results. In one analysis a onecentimeter electro-optic modulator constructed from lithium niobatetypically has a bandwidth of less the 10 Gigahertz.

In using organic materials systems, one obstacle to overcome is thedecay of the poled electro-optic response at the elevated manufacturingand operating temperatures dictated by current electronic technology.

For generally useful devices, higher temperature electro-optic thermalstability is required. In some manufacturing processes, short-termtemperature excursions can be high than 300 degrees C. In fabrication,the poling and curing temperatures of an electro-optic polymer forintegrated devices may often exceed this limit.

SUMMARY OF THE INVENTION

Accordingly, It is an object of the present invention to provide anelectro-optic material that does not suffer from the limitations ofprior materials used in the art.

It is a further object to provide a new class of highlyhyperpolarizability organic chromophors.

It is yet a further object of this invention to show a process forsynthesizing the novel highly hyperpolarizable organic chromphores.

Another object is to provide devices such as electro-optical modulatorsemploying the new class of novel highly hyperpolarizable organicchromphores.

These and other objects of the present invention will become clear fromthe detailed description of the invention and the claims included below.

DETAILED DESCRIPTION OF THE INVENTION

It is the purpose of this invention to make a nonlinear optical materialin a polymer host. The functional material is a nonlinear opticalmaterial. It is made up of a polymer and a nonlinear optical dye orchromophore.

Nonlinear optical chromophores or dyes are constructed from threesegments which include a donor material, a pi-conjugated bridge, and anacceptor. The donor is electron rich when compared to the acceptor andthe bridge allows communication between the donor and the acceptor. Tooptimize the molecular hyperpolarizability or beta, one must strike abalance between the electron donating of the donor side and the electronaccepting ability of the acceptor side such that the hyperpolarizabilityis optimized.

The current state of art chromophores have not been optimized for beta.The present invention chemically modifies a well studied acceptor togive rise to a more potent acceptor that does optimize the beta valuesin these chromophores. It does, however, not increase the ground statedipole or mu as expected. In addition it optimizing the beta values.

The following describes the chromophore or dye of this invention.

Where R′, R″, R′″, R″″, R′″″ can be selected from the group consistingof alkyl. aryl, a heteroatom, substituted alkyl and substituted arylgroups.

The following is the aldehyde may be used in this invention.

Where R′, R″, R′″, R″″, R′″″ can be selected from the group consistingof alkyl. aryl, a heteroatom, substituted alkyl and substituted arylgroups.

The following is the acceptor which can be employed in this invention.

Where R can be selected from the group consisting of alkyl. aryl, aheteroatom, substituted alkyl and substituted aryl groups.

The reaction here is the Knovenegal condensation and is accomplished byputting the reactants together in solvents. While catalysts which areconventionally used in the art can be employed, in many cases nocatalyst is required.

A preferred product in this invention is2-[4-(3-{3-[2-(4-{Bis-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-amino}-phenyl)-vinyl]-5,5-dimethyl-cyclohex-2-enylidene}-propenyl)-3-cyano-5-methyl-5-trifluoromethyl-5H-furan-2-ylidene]-malononitrile.This is made from{3-[2-(4-{Bis-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-amino}-phenyl)-vinyl]-5,5-dimethyl-cyclohex-2-enylidene}-acetaldehydewhich is reacted with2-(3-Cyano-4,5-dimethyl-5-trifluoromethyl-5H-furan-2-ylidene)-malononitrile.

To make this preferred product, the malononitrile acceptor is made byreacting 4,4,4-Trifluoro-3-hydroxy-3-methyl-butan-2-one with 2equivalents of malonitrile in the presence of a lithium hydroxidecatalyst.

The doner material is described in the literature and its preparation iswell known to those of ordinary skill in the art.

By following the above, the chromophore of this invention can be poledat lower field and has increased temporal stability. Temporal stabilityoccurs when the nonlinear optical properties are maintained over time.This is a result of a reduction in electrostatic interaction between dyemolecules.

1.

where R′, R″, R′″, R′″″ can be selected from the group consisting ofalkyl aryl, a heteroatom, substituted alkyl and substituted aryl groups.